1. Field of the Invention
The present invention relates to a composition for use in laser decomposition and to a pattern-forming material using the composition and, in particular, to a composition for use in laser decomposition, which can be utilized as a thick film, which has a high engraving sensitivity, which permits effective engraving with a low laser energy, and which has a good resolution, and to the pattern-forming material using the composition.
2. Description of the Related Art
Decomposable resins and decomposable resin compositions are those which undergo decomposition of resin in response to external factors such as a thermal factor, a mechanical factor, a photochemical factor, a radiation chemical factor or a chemical factor, and are widely known. Change in form (liquefaction or gasification) of the resins or compositions before and after their decomposition or change in properties or characteristics such as molecular weight, hardness, viscoelasticity, glass transition point (Tg), solubility or adhesion properties have been utilized in various fields.
Examples of such decomposable resins or decomposable resin compositions include bio-decomposable plastics intended for decreasing environmental influences of plastic materials (e.g., polylactic acid) and sustained-release materials for gradually releasing components such as drugs or perfumes used in the field of medicines and cosmetics or in the field of life science. However, these are gradually decomposable under the natural environment due to oxygen, light or enzyme, in vivo or in soils and are not materials which stably keep the initial state and, when exposed to external stimulation, rapidly undergo great change in properties.
Also, there have been developed resins decomposable by light or heat and adhesives which undergo reduction in adhesion properties in order to improve recycling convenience or simplify waste treatment. Further, it has been known to mix ceramics or carbon fibers with a decomposable resin and remove the decomposable resin by baking or the like to thereby form a porous material. However, these techniques treat and process the materials wholly and not in part to form a necessary pattern in necessary portions. In addition, a large energy is required to perform the decomposition treatment.
As an example of utilizing the techniques to image formation, there are known examples wherein a toner containing a thermally decomposable resin is used and change in properties of the resin due to heat upon heat-fixing is utilized to thereby ensure both storage stability as a toner and image fixing properties. However, the resin itself has not enough responsibility to patternwise stimulation.
On the other hand, as a pattern-forming material, there have widely been known, for example, photo resists which comprise a photo acid generator and an acid-decomposable resin and which, when patternwise exposed and, as needed, heat-treated, undergo patternwise decomposition of the resin, and then development-treated to form a pattern, as so-called chemically amplified resists. Such compositions have both storage stability and pattern-forming properties at practical levels but, for forming a pattern, a development step is necessary wherein processing conditions are sufficiently controlled. In addition, though the techniques can be applied to a thin film, it is difficult to apply them to form a pattern with a thickness of, for example, several ten μm or more.
It has also been known to form an image by utilizing a step of imagewise irradiating with a laser light to remove (ablation) part of a thin film to thereby form an image (JP-A-10-119436 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)). However, it is only common, general-purpose resins such as polyesters, polycarbonates and polyurethanes that are illustrated there as thermally decomposable resins, and the thickness thereof is as small as from about 1 to about 2 μm. In addition, there has been known an example of using a compound whose thermally decomposable properties are specified (JP-A-10-244751). However, with this example, too, the film thickness is as small as from about 1 to about 2 μm.
Further, as a mask material for paste printing onto a print wiring board, there have been disclosed a mask for forming a pattern of from about 100 to 200 μm utilizing a photo-decomposable resin sheet, and a process for its production (JP-A-8-258442). However, this document does not disclose specific compounds, and this technique requires a controlled development processing to form a pattern by adjusting the degrees of exposure and development.
On the other hand, as a technique for forming a pattern on a thick film by simple treatment, there has been known the technique of forming a pattern by, for example, laser processing. In this technique, imagewise irradiation with a laser light is performed to remove the substrate itself or change form or color of the substrate. For example, this technique is utilized to record information such as a lot number on a product (e.g., video tapes or consumer electric products) comprising various substrates. In this case, however, common resins are used as such for the substrates themselves.
Still now, in the technology of forming a pattern on a thick film by laser processing, a composition for use in laser decomposition having an excellent engraving sensitivity and an excellent resolution is being demanded.